Air-heater



AIR HEATER.

W. SPOELSTRA.

APPLICATIQN FILED SEPT B, 1920. 1,361,351

Mam

W. SPOELSTRA.

AIR HEATER.

APPLICATION FILED SEPT, 8. I920.

Patented Dec. 7, 1920.

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AIR HEATER.

APPHCATION FILED SEPT-8. 1920.

Patented Dec. 7,1920.

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AIR HEATER.

APPLICATION FILED SEPT. 8, I920.

Patented Dec. 7, 1920.

4 SHEETS-SHEET 4.

WATZE SPOELSTRA, OF SAN J'OSE,'CAL1FORNIA.

AIR-HEATER.

Specification of Letters Patent. Patented Dec. 7, 1920.

Application filed September 8, 1920. Serial No. 408,998.

for use in connection with drying appa-- ratus for supplying heated airthereto.

According to the invention, a combustion chamber or furnace is utilizedin which the fuel is burned, this chamber being completely encircled byan annular air inlet passage which communicates with a main heatingchamber into which the combustion chamber opens. Both the annular airpassage or chamber and the adjacent outer portion of the main heatinchamber are fitted with tubes, the rear en s of the air chamber tubesand the front ends of the heating chamber tubes being fitted in openingsin a change header plate which conjointly forms the rear wall of the airchamber and the front wall of the main heating chamber. The air chamberis open at its front for ingress of air, and the tubes therein projectbeyond said chamber and open into an an nular chamber which encirclesthe front end of the combustion chamber and which communicates with astack so as to produce the required draft. The rear ends of the tubes inthe main heating chamber open into an air collecting chamber from whichthe heated air passes through an exhauster and is piped to the drier orother point of use. The air collecting chamber is preferably equippedwith an auxiliary heating chamber which is located interiorly thereofand is provided with its own set of air inlet pipes;

the air heated in the auxiliary chamber discharging into the collectingchamber.

Owing to the above described construction and arrangement of parts, theair drawn in through the open-ended air chamber will circulate freelyaround the tubes therein and which convey the flue gases or gases ofcombustion from the main heating chamber and discharge theminto theannular chamber at the front of the combustion chamber, whence they passto the stack. On reaching the rear end of the air chamber, the airenters the tubes or Hues disposed in the main heating chamber and thenflows into the collecting chamber; the disposition of the tubes or fluesin the main heating cham her being such as to enable the flue gases tocirculate freely around and act directly on them, so that the air willbe heated to the proper degree by the time it enters the collectingchamber, While the flue gases will have given up a part of their heatbefore entering their exit tubes or flues. The currents of air and gastravel horizontally in opposite directions through their respectiveflues; the air passing through the air chamber entirely surrounding thegas flues or tubes therein, While the flue gases in the main heatingchamber entirely surround the air flues.

The auxiliary heating chamber has its front wall formed by the rear wallof the main heating chamber, so that the air supplied to the formerchamber through the auxiliary inlet tubes or flues will be rapidlyheated. These auxiliary flues may be equipped with suitable regulatingdevices to control the passage of the air therethrough and, hence, theamount of air re ceived in the collecting chamber, thereby providing forsemi-permanent regulation of the heater to the point of greatestefliciency.

Other improvements and advantages will become apparent in the course ofthe following description.

An embodiment of the invention is illus trated in the accompanyingdrawings, in'

which:'

Figure 1 is a central vertical section of the improved heater.

the chamber, so that the flue gases or gases of combustion will becaused to pass rearward through the chamber into'thesubsequently-described main heating chamber 3. The combustion-chamber isprovided-with suitable heating means 111 shown diagrammatically, in Fig.1, as in the form of an vspaced acomparatively slight distance behind asecond annular chamber 5, which encircles the extreme front portion ofthe combustion chamber and is closed by front and .back plates 6 and 7the outer or annular .wall of this chamber 5 having a discharge opening8 from which a flue 9 leads to the stack (not shown) The rear end-of theair chamber 4 is closed by a plate 10, hereinafter termed the changeheader plate, which conjointly forms the rear wall of that chamber, andthe front- .wall of the previously-mentioned main heating chamber 8,which is likewise of cylindrical form and has a diameter equal to thatof the outer wall of chamber 4,in other words, the combined diameters ofthe combustio'n chamber and the air chamber proper. The portion of thechange header plate 10 which is immediately behind the combustionchamber 1, is left open.

The back plate 7 of the discharge chamber 5 is formed with a circularseries of openings 11 which exactly aline with a coaxial series ofopenings 12 formed in the change header plate 10, these openings havingfitted therein the corresponding ends of a series of horizontal tubes orlines 13 serving to conveythe flue gases from the main heating chamber 3through the air chamber 4 into the above-mentioned discharge chamber 5;the 'said flues being spaced substantially equidi'stantly of the'wallsof the air chamher, so that the in-coming air can circulate freelyaround and along them during its progress through the air chamber and beheated in that way. The header plate 10 has formed in it, in addition tothe gas flue inlets 12, a plurality of circular series or rows ofopenings 14, all of which additional rows are concentric with oneanother and with the intermediate row 12. These openings 14, the twoinner rows of which have a slightly smaller diameter than the remainingrows, receive the front ends of rows of tubes or fiues 15, whose rearends lit in corresponding openings 16 formed in the rear plate 17 of themain heating chamber 3; both ends of the flues being left open, so thatthe air in the chamber 4 may be drawn therethrough and discharged intothe collecting chamber 18 which is located immediately behind thechamber 3 and has the same-diameter as that chamber. The fines 15: arespaced sufficiently far apart from one anotheriand from'the wall ofchamber 3 to perrnit'them to be entirely surrounded by thefiile gases inchamber 3wh1ch are thereaused tojgive Euip' a'portion of their heat,

with the result that the air in passing through the fiues is heated tothe required temperature.

The central portion of the main heating chamber contains no flues, aswill be understood from Figs. 1, 4 and 5; and the corre sponding portionof the end header plate 17 which conjointly forms the rear wall of saidchamber and thefront wall of the collecting chamber 18 is removed, theopening thus produced being covered by a detachable plate 19. The latterforms the front wall of an auxiliary heating chamber 20, which islocated within the chamber 18 and is supplied with air through anindividual set of short inlet lines 21, which extend at their front endsthrough openings 22 in the rear plate 23 of chamber 20 and at their rearends through openings 24 in the rear plate or end header plate 25 of thecollecting chamber 18. The flue openings 22 are disposed comparativelyclose to the edge of plate 23, which latter is further provided with acentral discharge opening 26 for the escape of the heated air into thecollecting chamber, from which it passes through an opening 27 in theend header plate or rear plate 25 into an exhauster (not shown) whichsupplies it to its point of use.

The plates which form the front and rear walls of the several chambersmay be mad in sections for convenience of construction, and forreplacement of tubes, as will be understood from Figs. 2 to 5 and 7 theair passage or chamber 4 may be subdivided into a number of separatepassages, if desired; and various other minor changes or additions mayberesorted to within the scope of the invention.

Means are provided in connection with the auxiliary inlet fines or tubes21 for controlling the air flow thercthrough, said means being hereshown as in the form of caps 28 (indicated in dotted lines in Fig. 1)which may be removably attached to any or all of these tubes. The tubesleft opened or uncapped bring in air of lower temperature for admixturein the collecting chamber with the air supplied thereto through the mainlines 15, so that the temperature of the air withdrawn through theopening 27 is the resultant of such admixture. Hence by Varyingthelnumber of auxiliary tubes left open, the temperature at which theair is piped off from the header may be corresp'ondingly modified withincertain limits, thereby providing for a regulation to the point ofgreatest efficiency. i

I claim as my invention 1. An air heater, comprising in combination, acombustion chamber; an annular air inlet passage encircling the same; aheating chamber located immediately behindthe combustion chamber and infree communication""therewith to permit the gases of combustion to passfrom the combustion chamber to the heating chamber; a series of finesarranged in the air passage and opening at their inlet ends into theheating chamber to convey the heated gases from said heating chamberthrough said passage and thereby heat the incoming air flowing throughthe passage; a series of air flues arranged in said heating chamber andaround which the heated gases in the heating chamber freely circulateprior to their entry into the gas flues, said air flues opening at theirinlet ends into said air passage; and an air collecting chamber behindsaid heating chamber and intowhich the outlet ends of the air fluesopen. 7

2. An air heater, comprising in combination, a combustion chamber; anannular air inlet passage encircling the same; a heating chamber locatedimmediately behind the combustion chamber and in freecommunicationtherewith to permit the gases of combustion to pass from the combustionchamber to the heating chamber, a series of fines arranged in the airpassage and opening at their inlet ends into the heating chamber toconvey the heated gases from said heating chamber through said passageand thereby heat the incoming air flowing through the passage; a gasdischarge chamber encircling the front of the combustion chamber andinto which the outlet ends of the gas lines open, said discharge chamberadapted for connection to a stack to create a draft therein; a series ofair flues arranged in said heating chamber and around which the heatedgases in the heating chamber freely circulate prior to their entry intothe gas flues, said air flues opening at their inlet ends into said airpassage; and an air c0llecting chamber behind said heating chamber andinto which the outlet ends of the air flues open.

3. An air heater, comprising in combination, a combustion chamber; anannular air inlet passage encircling the same; a heating chamber locatedimmediately behind the combustion chamber and in free communicationtherewith to permit the gases of combustion to pass from the combustionchamber to the heating chamber; a series of lines arranged in the airpassage and opening at their inlet ends into the heating chamber toconvey the heated gases from said heat:

ing chamber through said passage and thereby heat the incoming airflowing through the passage; a series of air flues arranged in saidheating chamber and around which the heated gases in the heating chamberfreely circulate prior to their entry into the gas flues, said air fluesopening at their inlet ends into said air passage; an air collectingchamber behind the heating chamber and into which the outlet ends of theair flues open; an auxiliary heating chamber located in said aircollecting chamber immediately behind the first-named heating chamber tobe heated thereby; and means independent of said air lines for supplyinair to the auxiliary chamber to be heatec l therein.

4. An air heater, comprising in combination, a combustion chamber; anannular air inlet passage encircling the same; a main heating chamber incommunication with the combustion chamber to receive the heated gases ofcombustion therefrom; means for conveying said gases from said heatingchamber through said air passage to heat the air flowing therethrough;an air collecting chamber; means for conveying the air from said passagethrough said heating chamber and into said collecting chamber; and anauxiliary heating chamber-located within said collecting chamber andhaving an air supply means individual thereto.

5. An air heater, comprising, in combination, a combustion chamber; anannular air inlet passage encircling the same; a main heating chamber incommunication with the combustion chamber to receive the heated gases ofcombustion therefrom; means for conveying said gases from said heatingchamber through said air passage to heat the air flowing therethrough;an air collecting chamber; means for conveying the air from said passagethrough said heating chamber and into said collecting chamber; anauxiliary heating chamber located within said collecting chamber; aseries of air inlet flues individual to the auxiliary heating chamberfor supplying air thereto; and means associated with the individual airinlet flues for controlling the flow of air therethrough.

In testimony whereof I affix my signature.

WATZE SPOELSTRA.

